Centrifugally operated switch



Feb. l2, 1952 G. J. BUTTERWORTH CENTRIFUGALLY OPERATED SWITCH 3Sheets-Sheet l Filed May 4, 1949 FIG. 3.

JNVENTOR. G/LBERT JMES BUTTERWORTH BY /v @im f ATTORNE S Feb 12, 1952 G.J. BUTTERWORTH 2,584,983

CENTRIFUGALLY OPERATED SWITCH FiledMay 4, 1949 3 sheets-sheet 2 7INVENTOR.

6 GILBERT JAMES euTTERwoRTH ATTORNE S Feb. l2, 1952 G. J. BuTTERwoRTH2,584,983

CENTRIFUGALLY OPERATED SWITCH Filed May4 4, 1949 3 Sheets-Sheet 3 G/LERT JAMES BUT TERWORTH ATTOR Patented Feb. 12, 1,9252

UNITED STATES PATENT CFFICE CENTRIFUGALL'Y OPERATED SWITCH n GilbertJames Butterworth, Chester, Pa., assignor to Sperry-"SurWell SurveyingCompany, Philadelphia, Pa., a corporation ofDelaware Applica-tion May4,1949, SerialNo. r91,349

16 Claims. 1

This invention relates to bore hole measuring and more particularly to acentrifugally operated control switch capable of providing repeatedclosing of an electric circuit such as may be used in connection with.the variousy instruments commonly employed in bore hole measuringapparatus.

In the art of bore hole measuring it is customary to go-devilinstruments down into a drill stem and by raising the drill stem `andrepeatedly operating the instruments at various levels within the boreholesecure a series of records ofconditions existing within the borehole correlated with the depths at which the various records were made.

It is common practice to record indications of bore hole inclination,temperature and other characteristics'by photographic or other meanswhich are generally electrically controlled.

Heretofore one of the problems associated kwith the procurement of sucha record has been that of providing suitable switching meanscontrollable from the surface of the ground for vterminating theoperation of Vthe recording` element or repeatedly initiating thesequence of recording operations at various depth levels. `Such a switchmeans must not be responsive to vibration, inclination, or impactoccurring during the normal passage of the instruments down through thedrill stem.

One device desirably used with such aswitching means is that describedin the patent to Roland Ring, No. 2,246,319, dated June 17, 1941, andalso illustrated in the patents to SmithNo. 2,301,757, dated Novemberl0, 1942, KothnyNo. 2,317,386, dated April 27, 1943, Emerson et al.`No.2,412,976, dated December 24, 1946, Kothny 2,415,249, vdated February 4,v1947, and Kothny No. 2,424,358, dated July 22, 1947. The Ringinstrumentis characterized by a slow continuous marking action, specificallyelectrolytic in character, whereby a record of the position of theinstrument within a bore holeis made only when the instrument remainsstationary for uan extended period of time. For a better understandingof the nature of the present invention-which is'not,-however, limitedfor its application to Vsaid instrument of the above `mentioned patents,the operation of said instrument may be described as follows:

If theinstrument is runinto a borehole, either Within a drill stem or inan openholadbymea'ns of a wire line or cable,-the movements ofthelinstrument incidental to its descent intot-he hole cause a. pendulumto -move about relative to a" recordmember, so that even though currentis continuously flowing from the pendulum to the record member, no pointof the record member is exposed to the current action for a suillcientlylong time to receive Va definite marking. When the instrument reachesthe level at which a record of inclination is to be made, it is broughtto rest and held in such position for a period upwards ofabout oneminute, with the result that the electrolytic action is concentrated atone point of the record member and an easily distinguishable spot ismade thereon. lv'f it is then desired to make one or more additionalrecords at other, levels, the instrument is moved to these successiveylevels and permitted to remain at them for different periods of time,with the result that marks diiering in intensity and/or size areproduced which, by their nature, can be identified with the particularlevels through a knowledge of the relative times during vwhich theinstrument wasstationary. Following the completion of the record orrecords, `the instrument is then withdrawn continuously from the holeand in this withdrawing movement, as well as in the periods of movementbetween the successive recordings, the pendulum will swing relative tothe record member so that again no obliterating markings are produced. y

rIn thecase of operation of the above type, the instrument is perfectlysatisfactory and requires no timing means whatever. However, a. commonpractice in the making of records with surveying instruments involvestheir being dropped freely through a drill stem so that they come torest in a position adjacent the bit. During this location in a positionof rest, a record is made Vunder the control of suitable timing means',and the instrument is then recovered when the bit is brought to thesurface. Generally speaking,such go-devil records are made at a timewhen it is necessary to bring the bit to the surface to check theprogress of the drill.. .Intheuse of said Ring instrument in go-devilfashion, the motionof the instrument through the drill stem prevents'themaking of any record during its fall, and a record is then made byhelding the drill stem stationary for a sunlcient period .0f time whilethe instrument rests ady,jacent the bit. If the drill stem was thenraised and dismantled by continuous work of the drilling crew, theinstrument would be subject to sui'- ciently continuous agitation, withonly quite limitedperiodsv of rest, so that no record obliteratingmarkings would be produced on the record member. However, it is notusual for a derrick crew to work continuously in removing a drill stemfrom deep holes, and generally speaking, even if some mechanical reasonfor delay does not occur, the workmen, after raising the drill stem partway, will take a short period of rest before proceeding further. If aninstrument of the Ring type is in the drill stem during such a period ofrest, or any other period of stationary condition of the drill stem, itwill be obvious that another record will be made which might beindistinguishable from the desired record unless a substantiallydifferent time of rest is involved, and even then in some rareinstances, particularly where the hole is substantially straight, thetwo records may overlap so that the significance of the original one islost. It is generally not desirable to rotate the drill stern duringsuch a period of interruption of its withdrawal, and consequently, suchrotation is not a practical solution to the problem.

In order to avoid the diiiiculties described in go-devil operations, theRing instrument has been provided with various circuit interruptingdevices as disclosed in said Smith, Emerson et al. and Kothny patents.

The present invention relates to the provision of means for terminatingthe recording action at a desired time, being particularly useful fortermination of the recording action following the completion of a singlerecord or a series of records. This means constitutes, in one aspect, animprovement over the current interrupting means of the patents referredto above.

As an example of the type of instriunen'ts which may have theiroperation repeatedly initiated attention is directed to the patent toWilliston et al. No. 1,960,038, dated May 22, 1934, disclosing a deviceconstituting means for obtaining a substantially continuous record ofthe deviation of a bore hole throughout its length and including meansfor automatically photographing simultaneously the position of agyroscope, a bubble, and a time piece, from which the deviation of ahole may be readily determined at various points along its length. rTheswitching apparatus of the present invention may be employed to enablethe drill crew to repeatedly initiate the operation of an instrumentsuch as disclosed by said Williston et al. patent and thereby reduce theloss of lm resulting from the great number of pictures needlessly takenby that instrument while the instrument is being moved from one positionto another within the bore hole.

The present switching means and a film moving means such as is disclosedby the Williston et al. patent may be employed in connection withinstruments such as are disclosed in the patents to Hewitt No.2,116,350, dated May 3, 1938, Hewitt et al. No. 2,169,342, dated August15, 1939, and in the application of Einar T. Young, Serial No. 757,790,filed June 28, 1947. These disclosures show single shot photographictype instruments for recording bore hole survey information. In eachinstance by the addition ofY a lm moving means controllable by thepresent switching means these instruments may be modined into multipleshot instruments capable of repeated operation initiated by the drillcrew at the surface of the earth.

It will be evident as the description proceeds for the control ofelectrical, acoustic, radioactive or other logging apparatus or thelike.

One of the most desirable methods for controlling operations such asreviewed above is by a centrifugally operated switching means responsiveto rotation of the drill stem. However, when the drill bit is raisedfrom the bottom of the drill hole and the drill stem is rotated at anyappreciable speed, because of the great length of the free hanging drillstem there is a tendency for the drill stem to whip with a very greatpossibility of damage or breaking resulting.

It is an object of this invention to provide a switch which will makeContact at relatively low speeds of rotation of the drill stem. v

It is another object of this invention to provide a centrifugal switchwhich will not make contact as a result of vibration, impact, orinclination such as would result from general handling or passage of theswitch within the bore hole, but which will establish an electricalcontact when rotated above a predetermined speed.

These and other objects of the invention relating particularly todetails of construction and operation will become apparent from thefollowing description, read in conjunction with the accompanyingdrawings, in which:

Figure 1 is an elevation of the switch assembly partially in sectionshowing iioating pendulums in an outward position such as would resultfrom rotation of the switch assembly;

Figure 2 is a transverse section taken on the plane 2-2 indicated inFigure 1 and showing in particular the pendulum sockets;

Figure 3 is a section taken on the plane 3 3 indicated in Figure lshowing the pendulums and the electrical contacts closed thereby, thisfigure diagramming the electrical connections;

Figure 4 is a diagrammatic representation of an electrical circuitemployed when utilizing the present invention to terminate a recordingoperation;

Figure 5 is a diagrammatic representation of a device employing thepresent invention to repeatedly initiate recording operations;

Figure 6 is a development of the surface of the timing drum associatedwith the device shown in Figure 5;

Figure 7 is a fragmentary elevation partly in section showing amodication of the switch assembly;

Figure 8 is a transverse section taken on the plane 8-8 indicated inFigure 7 showing the pendulums and the electrical contacts openedthereby, this figure diagramming the electrical connections; and

Figure 9 is a diagrammatic representation of an electrical circuitemployed when utilizing the modification of the invention shown inFigures 7 and 8 to terminate a recording operation.

The centrifugally operated control switch comprises a sleeve 4 made of asuitable plastic or other electrical non-conductive material containinga uid 6 which is preferably a good grade 0f oil, such as a transformeroil, having high dielectric properties and resistance to oxidation. Inthis uid are floated pendulums l. The pendulums are desirably formed ofaluminum or other light metal tubing sealed at the upper ends by capsincluding pointed projecting stems 8 and at the lower ends by silvercoated contact caps I8.

The pendulum stems 8 seat by oating in sockets 9 of screws I0 which arescrewed into tapped bores l2 of a non-conductive member I4. The

member I4 is screwed. yinto position in the u pper end of the sleeve Il.and vthe sleeve is sealed by plug member I6 which is screwed into thesleeve and cementedto prevent oil leakage. The member I6 bears againstthe member |4 thereby locking the member I4 rigidly in position.

The lower end of the sleeve 4 is plugged by insulating member 22 whichis screwed into place and cemented to prevent oil leakage. In member 22are mounted contact bars 2U positioned so as to be contacted by lowerends I8 of the pendulums when the pendulums are in outward position.Member 22 also contains slots I9 serving to retain and guide the freeends of the pendulums to insure proper contacting with contact member2U. The pin |1, mounted in and extending above member 22 at the junctionof the slots I9, is provided to prevent the pendulums from falling outof their respective slots when the instrument is inclined.

When the control switch is at rest in a vertical position the pendulums.will, by virtue of their weighted lower ends I8, float in verticalpositions, grouped together in the center of the liquid chamber andassume positions under the socket screws I8. When the switch is rotatedat a suiiicient speed the lower ends of the pendulums will move outwardin response to centrifugal force and establish contacts between each ofthe pairs of contact bars 20 thus completing the circuit from the leadwire 24 through jumper wires 25 and 26, connecting the lower ends ofbars 20, to lead wire 21. These contacts will be iirm and positivecontacts vby virtue of the centrifugal force acting on the pendulums.

It is obvious that inclining the switching assembly or submitting theswitch to horizontal impact can not possibly cause all three of thependulums to :be in outward Vpositions simultaneously. Thus, only byrotating the assembly can a continuous circuit be established betweenthe lead wires. The switch, therefore, can be utilized to establishcontact in response to rotation of the drill stem at a speed above thepredetermined value and will not establish contact as a result ofinclination, impact or vibration as would occur during the lowering ofthe switch in a drill stem.

Inasmuch as the angle assumed by each of the pendulums is dependent uponthe speed of rotation of the switch assembly the value of speed at whichswitch contact is established, other factors being equal, is dependentupon the length of the pendulums. Thus, reducing the length of thependulums will cause contact to occur at higher speeds and increasingthe length of the pendulums will cause contact to occur at lower speeds.Heretofore in bore hole logging the problem has been to provide reliablecontact making means which would operate at sufficiently low speeds ofrotation. The present invention will provide desirably reliable contactat speeds below 50 R. P. M. and, by varying the length of thependulurns, contact can be made to reliably occur at various -reasonablyselected and predetermined values. of speed.

The viscosity of the oil in which the pendulums are floated will affectthe rate at which the pendulums will move outward, in response to thecentrifugal force resulting from rotation, and the rate at which theywill move inward, due to the action of gravity alone when the switch isat rest. This rate of motion of thev pendulums. can .be altered bychanging the viscosity of the oil; to produce` characteristics ofoperationv eenerally desirable for any specific operating conditions..

Figure 4 shows the present .invention employed in connection with theRing type instrument which has been hereinbefore discussed.

There is generally shown at 40 the contact elements of the presentinvention with lead wire 24 connected to ground. The lead wire 21 isconnected through battery 42 and conductor 44 to solenoid coil 48 andthrough lead wire 50 to the common ground line 52. When this instrumentis go-deviled into a drill stem and comes to rest at the bottom thereofcurrent passes from the battery 54 through the current limiting resistor55, the pendulum member 60, the contact point 62, and electrochemicalrecord member 64 to the common ground 52 and returns to the batterythrough switch lead wire 66, switch contact lever 61, switch contactpoint 6.8 and lead Wire 18. It

will be noted that the switch contact lever .61 is held nrmly againstcontact point 68 .by the action of latch member 12 and spring 14.

If the instrument is at rest in one position for sufficient .length oftime electrochemical action will cause an indication to be madeonrecording member 64 under the .contact point 62. After the drill stemhas been successively raised and held at rest at the various levels atwhich records are desirably obtained, the drill stem is then rotated atsufficient speed to cause the centrifugal contact switch 40 to closecompleting the circuit through the switch 40, the wire 21, battery 42,the wire 44, the solenoid coil 48, the wire 50 and ground 52 therebyenergizing the solenoid coil 43 and drawing the contact lever 61 againstthe end of the solenoid core in which position it is locked by latchmember 12 ras a result of the action of the latch spring 14. Contact isthen broken between contact point 68 and contact lever 61 and thus thependulum contact point 62 is deenergized and no further records will bemade upon record member 64. When the instrument is removed from thedrill stem, record member 64 is` removed, a new record member isinstalled and the switch contact lever 61 is reset in prepai ration forthe next operation of the instrument.

Figure 5 is a schematic showing of the present invention employed toinitiate means for photographing a floating compass element s-uch as isdisclosed in the previously mentioned Young application.A There is shownat 40 the contact elements of the present invention. Lead wire 21 isconnected through conductor 81 to a battery 90 the other side of whichis grounded to a common ground 80. The conductor 81 is connected betweenthe battery 90 and brush contact 83 which bears upon the surface of thedrum contactor 92. The lead wire 86 from the centrifugal switch isconnected to brush contact 82 bearing on the drum 92.

The motor 94 is connected through lead wire 85 to contact brush 8| andthe motor is connected to the common ground through leadwire 96. Alsobearing on the contact drum is brush member 84 which is connectedthrough lead wire 88,v lamp 91, conductor 98 and lamp 99 to the commonground 80..

The motor 94 acts through shaft |02, spurv gears |04 and |08, shaft ||0,worm gears ||2 to drive the drum 92. Mounted on the drum 92 is aconventional geneva drive guide cam ||4 anddrive pin I|6 which engagesthe geneva gear member 8. Mounted on the face of the geneva member |||lis the pulley |.|:9 mounting 7 the belt |20. The belt passes over thepulley |2| which is rigidly xed to film spool |22.

The lm |24 is carried by spools |22, |23, |25 and |26 and passes throughfilm guide |28.

There is suitably disposed at |30 a lens which is located to properlyfocus the light originating from the lamps 98 and 98 and reflected fromcompass element |3| upon the film |24 contained within the film guide|28.

The compass element generally shown at |3| comprises glass members |32and |34 ground to provide an accurate spherical opening |36 in which islocated a liquid |38 supporting a float which comprises a body |40 oftransparent plastic material. Secured to the body |40 by cement is asecond plastic member |42 in the form of a disc provided with a seat fora permanent magnet |44 which is in the form of a ring permanentlymagnetized and cemented to the member |42. A cap member` |46 is cementedto the member |42 and provides a closure for the air space whichprovides the necessary buoyance. The surface |48 of member |42 carriesengraved markings which may consist of a radial line at its peripheryfor the indication of azimuth and concentric circles for the measurementof inclination. On the lower' surface of the member |42 there may beengraved a cross or other marking |50 serving when read against theconcentric circles to indicate the degree of inclination. The cap |46may be provided on its interior surface with a white coating to form adefinite background for the photographing of black engraved markings.Alternately, the markings may be engraved in white in which case the capmay be coated to provide a black background.

There is shown in Figure 6 the development of the surface of the contactdrum 92. Bearing thereon are the previously mentioned contact brushes8|, 82, 83 and 84. When the motor 94 is causing the drum to rotate thedrum surface proceeds past the brushes in the direction shown by thearrow |60. The surface of the drum is divided into the conductive area|62 and nonconductive area |63. The position of the brushes shown atFigure 6 is that existing when the motor 64 is inoperative, thecentrifugal switch member 40 is in an open position and the drumcontactor is in position to begin a sequence of operation. The operationof the entire instrument can now be reviewed as follows:

When it is desired to operate the recording instrument the drill stem isrotated at a predetermined speed which is known to be suicient to causethe pendulums of the centrifugal switch element to fly outwardly andestablish contact through the switch as has been hereinbefore reviewed.

When the centrifugal contact switch 40 is rotated contact is establishedthrough the centrifugal switch member and conductors 21 and 86 betweenthe battery S0 and the brush 82. The brush 82 is bearing on theconductive surface of the drum. Also bearing on the conductive surfaceof the drum is brush 8| which is connected to the motor S4. Thus, assoon as contact is established through the centrifugal switch the motorwill operate and cause the drum 82 to rotate.

The drill stem must be rotated to maintam contact through thecentrifugal switch during time interval (a) until the drum 92 hasrotated sufciently to bring the conductive surface |62 to brush member83 which is connected to conductor 81 directly to the battery 90. Atthis time rotation of the drill stem is arrested, the motor proceeds todrive the drum, and during the time interval (b) the pin I6 engages theGeneva drive and draws the lm from the spool |23 through the film holder|28 and on to spool |22 thereby presenting an unexposed portion of filmwithin the film holder |28 in anticipation of the new photograph whichis to be made. At the completion of time interval (c) brush 84 isbrought to bear upon the conductive surface of the drum causing thelamps 91 and 99 to be illuminated for the period of time (d) duringwhich the position of the compass element is photographed. At theexpiration of time interval (d) the brush member 84 passes from theconductive surface to the non-conductive surface and the lamps areextinguished. At the completion of time interval (e) the contact brush83, which is connected through conductor 81 to the battery 9D, passesfrom the conductive surface to the non-conduc tive surface of the drumthereby deenergizing the conductor and the motor 94. Thus the rotationof the drum ceases.

It will be observed that time interval (a) during which the drill stemis rotated is relatively short compared to the time interval (c). Thus,ample time is provided for the drill stem and the compass member to cometo rest and all parts to be stationary before the photographic record ismade.

After the completion of a cycle of operation, the drill stem can beraised any desired extent by the removal of sections at the surface ofthe ground and, when the instrument is thus raised to a new location inthe drill hole at which recordings are to be made, the drill stem isagain rotated and the instrument passes through a new sequence ofoperation. Thus numerous records can be made at various levels in thedrill hole without imposing on the drill crew a fixed time schedulepresenting intervals during which they must position the drill stem forthe next recording and between which they may not rock the instrumentwithout destroying the recording. When employing the present inventionthe unavoidable delays which may occur at the surface of the groundpreventing a drill crew from maintaining such a fixed time schedule donot interfere with the making of the records nor do they jeopardizethose records already made. By use of the present invention theinstrument will operate only when such operation is initiated byrotation of the drill stem by the drill crew.

Figures 7 and 8 show a modification of the invention in which thependulums, and the pendulum mountings in the upper portion of the sleeve4, are identical with those described in connection with Figure 1.However, the contact arrangement mounted in the insulating member 22 inthe lower portion of the sleeve is modified. The contact bars 202 and204, mounted in the insulating member 22, are located in positions so asnot to be contacted by the lower ends of the pendulums |8. Twistedaround and soldered to each of the bars 202 is one end of each of theconductive spring wires 206. The other end of each of the wires 206, asa result of its own spring action, makes a positive contact with the bar204.

The pendulums when moving outwardly in response to centrifugal force, ashas been hereinbefore described, will bear against the contact wires 206deecting the wires and breaking the contacts between the wires 206 andthe bars 204. The bars 202 and 204 project downwardly through theinsulating member 22. As diagrammed in Figure 8 the lead wire 208isconnected' tov each of` the lower ends of the barsv 202- and the leadwire- 210 is ccnnected`4 toeach of the lower ends of the bars 204. Itwill be evident that inclination, vibration or'impact may eause-one-orpossibly twoof theA pendulums to moveoutwardly' and bear upon a Contactwire Bv suilciently tov open the contact between the Wire 206 and thebar 204. However, it can be only as a result ofrotas tion of the switchyassembly that all threeof the pendulums` will bear upon the contactwires and cause all three of the contacts' to beopenat the same time.Thus, with the three contacts connected in parallel it can only be as aresultv of rotation that the circuit `betweenl lead wire 208 and 2*!'0vwilll be brok-en. K

This modification of the switch assembly may be employed in connectionwith the above mentioned' Ring instrument in the circuit shown in Figure9 in which there is generally'shown at 2 |-2 the contact arrangements ofthe modification cf the'invention shown in Figures '7' and. 8A with thelead wire 2| 0 connected to the common ground wire 222 and the lead wire208'connected through the battery 214, and through lead-wire 2|5 to thecontact ZIB. The contact arm 2|.8 is connected through the solenoidcoilv 220 to the common ground" 222.

One side of-the battery'224 is connecte-d through lead wire 2-28` to thecontact point 230, and the contact arm 23?. is connected through leadwire 234 to the common ground 222. The other side of thefbattery 224 isconnected through thecurrent limiting resistor 56; the pendulum member60, the contact point 62', and an electrochemical record member 64 tothe common ground' 222'.

When this modiiication` of the instrument is prepared for go-devillingintothe drillv stem the push button 236 is manually depressedclosing thecontact arm. 2i|8 against contact point 21.6 thus initiating a currentow vfromthe battery 2l4 throughy the lead' wire 215, the contact ZF6,con*- tact arm 218', armature coil 220 common ground 222, and thecentrifugal switch. assembly2ll2 back to the battery 214; The magneticeld inducedy bythe current passing through thefarmature coil 220 willhold the Contact arm. 218' against the end of thearmature and will alsopull'inA the contact arm 232 against the otherv end' of the' arma-- turethereby establishing contact between the contact point 230 and thecontact arm 232.

The closing of contactv 230 will permit a current to fiow from thebattery224 through' the current limiting resistor 56, the lpendulummember 6'0, contact point 62, electrochemical record memberv 64, commonground 222', lead Wire; 234, contact arm 232, Contact point 230 and thelead wire 22-3 back to the battery 224.

With the recording apparatus thus energizedv the instrument isgo-deviled intol a drill stem.y After a succession of records havefbeen'made, as has been hereinbefore described,` and it isxdesired tointerrupt the record making process and retrieve the record element, thedrill stem will'beirotated at a sufficienti speed toE cause. thependulums to move outwardly generally simulta.

neously and to break the circuit between lead wires 208 and. 210. Thusythe current iiowing from the battery 2M through the armature coil 220will bek interrupted. The field through the armature core will collapseand the tension springs 238 and 240 will open the contact arms 213%and232ai and will hold. the contact arms open against vibration,inclination or impact, thus permanently interrupting both the current owthrough the armature coil 220 and the current flow through thecontactpoint 62 and the electrochemical recordmember B4' until such time as theinstrument is retracted and the push button 236 is manuallydepressedreestablishing the current flow from the-battery 2 I4 throughthe armature coil 220 recreating the magnetic field in the armaturecore.

It will be evident that numerous Variations, such as anchoring thependulums at their lower ends and allowing the upper ends to respond tocentrifugal force, employing various modications of the contactarrangement, and the like, may be made in details of the embodiment ofthe invention without departing from the scope thereof as dened in thefollowing claims.

Wha-t I claim andv desire to protect by Letters Patent is:

l. A switch assembly for initiating electrical contact'in a bore holemeasuring apparatus comprising a chamber containing a fluid medium,floating contact means in said medium and stationary contact means insaid medium, said oating contact means contacting said stationarycontact means in response to the centrifugal force acting on saidfloating contact means when the switch assembly is rotated.

2. A switch assembly for initiating electrical contact in a bore holemeasuring apparatus comprising a chamber containing a fluid medium,floating contact means in said medium mounted inwardly within saidchamber and stationary contact means in said medium mounted outwardlywithin said chamber, said floating contact means moving outwardly andcontacting-said stationary contact means in response to the centrifugalforce acting on said floating means when the switch assembly is rotatedat a rate inexcess of a predetermined rate of rotation.

3. A switch assembly for initiating electrical contact in bore holemeasuring apparatus comprising a chamber containing a fluid medium, aplurality of pendulum members floating in said medium, and stationarycontact members mounted outwardly of one end of each of said pendulummembers, the ends of'each of said pendulums contactingv the! contactmembers in respouse` to the centrifugal force acting on the pen'- dulumswhen the switch assembly is rotated.

4. Apparatus for controlling the operation of a borehole measuringinstrumentr including an electrically operated contact means, meansproviding a source ofv electric current, and a centrifugally'op'eratedswitching means, said means connected and arranged to provide a flow ofcurrent from said current sourcev through said electrically operatedcontact means whenV said cen'- trifugally operated switching means ismadek conductive as a result of rotation thereof.

5. Apparatus for controlling the operation of a'bore hole measuringinstrument including an electrically operated contact means, means providing a source of electric current, and a centrifugally operatedswitching means comprising..

a chamber containing a fluid andy contact members iioating in saidiiuid, said means. connected and arranged to provide a ilow of' currentfrom said' current source through said electrically operated contactmeans` whenw said centrifugally operated switching means ismadeconductive as a result of rotation thereof.

6. Apparatus for controlling the' operation of a bore hole measuringinstrument including an electrically operated contact means, meansproviding a source of electric current, and a centrifugally operatedswitching means comprising a chamber containing a fluid, floatingcontact members, and stationary contact members, said means connectedand arranged to provide a flow of current from said current sourcethrough said electrically operated contact means when said centrifugallyoperated switching means is made conductive as a result of contact beingestablished between the floating contact member and the stationarycontact members when the switch assembly is rotated.

7. A switch assembly for interrupting an electrical circuit in a borehole measuring apparatus comprising a chamber containing a fluid medium,floating means in said medium and contact means mounted in said chamber,said floating means bearing against said contact means in response tothe centrifugal force acting on said floating means when the switchassembly is rotated and opening the contact means.

8. A switch assembly for interrupting an electrical circuit in a borehole measuring apparatus comprising a chamber containing a fluid medium,floating means in said medium mounted inwardly within said chamber andcontact means mounted outwardly within said chamber, said floating meansmoving outwardly and bearing against said contact means in response tocentrifugal force acting on said floating means when the switch assemblyis rotated at a rate in excess of predetermined rate of rotation andopening the contact means.

9. A switch assembly for interrupting an electrical circuit in a borehole measuring apparatus comprising a chamber containing a fluid medium,a plurality of pendulum members floating in said medium mounted inwardlywithin said chamber and contact means mounted outwardly of each of saidpendulum members within said chamber, the ends of each of said pendulumsbearing against said contact means in response to the centrifugal forceacting on said floating means when the switch assembly is rotated at arate in excess of a predetermined rate of rotation and opening thecontact means.

l0. Apparatus for controlling the operation of a bore hole measuringinstrument including an electrically operated contact means, meansproviding a source of electric current, and a centrifugally operatedswitching means comprising a chamber containing a fluid and membersfloating individually in said fluid, said means connected and arrangedto provide a flow of current from said current source through saidelectrically operated contact means when said centrifugally operatedswitching means is at rest, and interrupting the flow of current whenthe switch is made non-conductive as a result of rotation thereof.

ll. Apparatus for controlling the operation of a bore hole measuringinstrument including an electrically operated contact means, meansproviding a source of electric current, and a centrifugally operatedswitching means comprising achamber containing a fluid, floatingmembers, and contact members, said means connected and arranged toprovide a flow of current from said current source through saidelectrically operated contact means when said centrifugally operatedswitching means is at rest, and interrupting the flow of current whenthe sWzQh,

rotated and made non-conductive by the floating members acting upon thecontact members in response to centrifugal force acting upon saidfloating members when the switch assembly is rotated.

12. A switch assembly for controlling an electrical circuit in a borehole measuring apparatus comprising a chamber containing a fluid medium,floating means in said medium and contact means mounted in said chamber,said floating means bearing against said contact means and effectingcontrol of said contact means in response to the centrifugal forceacting on said floating means when the switch assembly is rotated.

13. A' switch assembly for controlling an electrical circuit in a borehole measuring apparatus comprising a chamber containing a fluid medium,floating means in said medium mounted inwardly within said chamber andcontact means mounted outwardly within said chamber, said floating meansmoving outwardly and bearing against said contact means and effectingcontrol of said contact means in response to the centrifugal forceacting on said floating means when the switch assembly is rotated.

14. A switch assembly for controlling an electrical circuit in a borehole measuring apparatus comprising a chamber containing a fluid medium,a plurality of pendulum members floating in said medium mounted inwardlywithin said chamber and contact means mounted outwardly of each of saidpendulum members within said chamber, the ends of each of said pendulumsbearing against said contact means and effecting control of said contactmeans in response to the centrifugal force acting on said floating meanswhen the switch assembly is rotated.

15. Apparatus for controlling the operation of a bore hole measuringinstrument including an electrically operated contact means, meansproviding a source of electric current, and a centrifugally operatedswitching means comprising a chamber containing a fluid and membersfloating individually in said fluid, said means connected and arrangedto control the flow of curd rent from said current source through saidelectrically operated contact means when said centrifugally operatedswitching means is made operative as a result of rotation thereof.

16. Apparatus for controlling the operation of a bore hole measuringinstrument including an electrically operated contact means, meansproviding a source of electric current, and a centrifugally operatedswitching means comprising a chamber containing a fluid, membersfloating individually in said fluid, and contact members. said meansconnected and arranged to control the flow of current from said currentsource through said electrically operated contact means when saidcentrifugally operated switching means is made operative as a result ofcontact being established between the floating members and the contactmembers when the switch assembly is rotated.

GILBERT JAMES BUTIERWORTH.

REFERENCES CITED UNITED STATES PATENTS Name Date Kohl T?, Nov. 16, 1948Number

